Radar loop of Hurricane Dolly
Hurricane Dolly has become the second hurricane of the 2008 hurricane season. Dolly is barely a hurricane, and is still struggling to build a complete eyewall. Visible satellite loops show an eye developing, and heavy thunderstorm activity continues to increase near the core of the storm. Dolly has good upper-level outflow to the west and north, but restricted on the south side, where an upper level low pressure system is still interfering. Maximum surface winds measured by the SFMR instrument on the current Hurricane Hunter aircraft inside Dolly were 74 mph (65 kt), measured at 4:17 pm EDT. Brownsville, Texas long-range radar shows the eyewall is complete on Dolly's west side, but is struggling to get established on the east side. Radar estimated rainfall amounts of 1/10 of an inch have fallen on the Texas/Mexico coast so far, thanks to the outermost spiral bands of Dolly.
The intensification potential for Dolly remains high, but until Dolly can form a full eyewall, it won't be able to take full advantage of the favorable environment. Wind shear over Dolly is about five knots, and is expected to remain below ten knots over the next two days. An upper level high pressure system is moving into place over the storm, which should enhance Dolly's upper-level outflow and allow more rapid intensification. Dolly is over waters of 29°C. The waters cool to about 28°C by midnight tonight as Dolly approaches the coast and passes over a cool ocean eddy. The depth of the warm waters Dolly is over has decreased, and the Tropical Cyclone Heat Potential has fallen from about 40 to 20 kJ/cm**2. This decreases the potential of rapid intensification. Our skill in making intensity forecasts is poor, but it currently appears that Dolly only has enough time to intensify into a Category 1 hurricane. A Category 2 hurricane still a possibility, though. The track forecast
The track forecast has changed little since this morning, with the various computer models predicting pretty much the same behavior as they did 12 hours ago. Four models are predicting a landfall in northeastern Mexico--the UKMET, ECMWF, NOGAPS, and GFS--and two models are predicting a Texas landfall--the GFDL (just north of Brownsville) and the HWRF (near Corpus Christi). Dolly could come ashore anywhere within the cone of uncertainty, and one should not assume the storm will track down the "skinny black line" NHC has drawn through their official forecast. The timing of Dolly's landfall, as predicted by the computer models, will be anywhere from 8 am - 10 pm Wednesday. However, the GFS and ECMWF hint that Dolly may stall out right by the coast Wednesday, and some slow and erratic motion is possible tomorrow before the storm finally comes ashore.
SOURCE
From NOAA
500 PM EDT TUE JUL 22 2008
DOLLY IS BEING CLOSELY MONITORED BY THE NWS RADAR FROM
BROWNSVILLE...NOAA BUOYS..SATELLITE AND VERY IMPORTANTLY...BY AN
AIR FORCE HURRICANE HUNTER AIRCRAFT. THE RADAR IS MEASURING 75
KNOTS AT ABOUT 20 THOUSAND FEET AND SHOW NUMEROUS RAINBANDS ALREADY
APPROACHING THE COASTS OF NORTHEAST MEXICO AND SOUTHERN TEXAS.
DVORAK ESTIMATES SUGGEST THAT DOLLY IS A HURRICANE AND WIND DATA
JUST RECEIVED FROM THE RECONNAISSANCE AIRCRAFT HAVE CONFIRMED IT.
INITIAL INTENSITY IS 65 KNOTS. WITH THE PREVAILING LOW
SHEAR...DOLLY IS FORECAST TO REACH THE COAST A LITTLE BIT STRONGER.
DOLLY IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 9 KNOTS.
THIS GENERAL TRACK SHOULD CONTINUE FOR THE NEXT 24 HOURS WITH A
SMALL DECREASE IN FORWARD SPEED. ON THIS TRACK...THE CORE OF DOLLY
SHOULD BE NEAR THE US/MEXICO BORDER WITHIN THE WARNING AREA ON
WEDNESDAY. DOLLY IS LARGE CYCLONE AND TROPICAL STORM FORCE WINDS
WILL BEGIN TO AFFECT THE AREA TONIGHT. AFTER LANDFALL...DOLLY
SHOULD TURN MORE TO WEST AS A SUBTROPICAL RIDGE BUILDS TO THE NORTH
OF THE CYCLONE. MOST OF THE TRACK MODELS ARE IN GOOD AGREEMENT
BRINGING THE CORE OF DOLLY INLAND IN ABOUT 24 HOURS. IT SHOULD BE
RE-EMPHASIZED THAT...DUE TO THE INHERENT UNCERTAINTIES...ONE MUST
NOT FOCUS ON THE EXACT LANDFALL POINT IN THIS FORECAST.
DUE TO THE SLOW MOTION AT LANDFALL...DOLLY COULD DUMP VERY HEAVY
RAINS IN THE AREA.
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